Recommendation requested for two items used for sponges (sugar and a baking pan)

First is where one obtains castor sugar. A lot of the sponge recipes I come across calls for castor sugar (aka baker's sugar), and it's an item that's difficult to track down. I think I can get it from Amazon (in a 4-lb package), but was wondering if there may be alternatives.

The next is a recommendation of a baking pan (relatively large-sized) for baking said sponge (goal here is so that I can cut the thing in half and stack the layers). Something that will stand up to the baking temperature without deforming. Also looking for something without any fluorinated polymer coatings.

Would appreciate suggestions on either of these.

Pulse "regular" sugar in a food processor or blender. Honestly any commercial refined sugar will be fine enough. Castor sugar is just small crystal sugar.

For sponges, I like silicon sheets/pans. I put parchment in the bottom. I hate the way they don't hold their shape when picked up, but love the way they don't over-brown the edges and are easy to remove the sponge from when done.

spopepro is right - castor sugar is just really fine sugar. But if you're unsure, King Arthur sells it:

https://shop.kingarthurbaking.com/it...-special-sugar